Earth Sciences Commons^™

Stable Isotope Study Of Water-Rock Interaction And Ore Formation, Bayhorse Base And Precious Metal District, Idaho, Robert R. Seal Ii, Robert O. Rye

United States Geological Survey: Staff Publications

The Bayhorse base and precious metal district situated east of the Idaho batholiths in south-central Idaho. The ores occur near the Nevada Mountain granitic stock as veins cutting the lower Paleozoic Ramshorn Slate and the Garden Creek Phyllite, and as fillings around breccias fragments within the Bayhorse Dolomite. The veins are dominated by siderite and tetrahedrite, with lesser quartz and galena, whereas the breccias ores dominantly comprise only quartz and galena. Mineralization and intrusive activity were contemporaneous during Cretaceous time. Fluid inclusion and stable isotope data indicate that mineralization formed from hot (ca. 375° -225°C), CO₂-rich (≤8.3 ± …

Superambient Heat Capacities Of Synthetic Stibnite, Berthierite, And Chalcostibite: Revised Thermodynamic Properties And Implications For Phase Equilibria, Robert R. Seal Ii, Richard A. Robie, Paul B. Barton Jr., Bruce Hemingway

United States Geological Survey: Staff Publications

Stibnite (Sb₂S₃), berthierite (FeSb₂S₄), and chalcostibite (CuSbS₂) are important antimony-bearing minerals. Stibnite is the main ore mineral of antimony and occurs as an important accessory in many epigenetic ore deposits, especially in later stages of deposition or in peripheral facies of mineralization. Berthierite is a common accessory mineral in antimony deposits. Its occurrence, particularly in gold-antimony deposits, has received considerable scientific attention. Furthermore, stibnite, berthierite, and chalcostibite represent important reference phases for understanding phase equilibria in more complex systems, such as those containing tetrahedrite-tennantite solid solutions.

Residence Times In River Basins As Determined By Analysis Of Long-Term Tritium Records, Robert L. Michel

United States Geological Survey: Staff Publications

The US Geological Survey has maintained a network of stations to collect samples for the measurement of tritium concentrations in precipitation and streamflow since the early 1960s. Tritium data from outflow waters of river basins draining 4500-75 000 km² are used to determine average residence times of water within the basins. The basins studied are the Colorado River above Cisco, Utah: the Kissimmee River above Lake Okeechobee, Florida; the Mississippi River above Anoka, Minnesota; the Neuse River above Streets Ferry Bridge near Vanceboro, North Carolina; the Potomac River above Point of Rocks. Maryland; the Sacramento River above Sacramento, California: …

Introduction To Special Section On The Cajon Pass Scientific Drilling Project, Mark D. Zoback, Arthur H. Lachenbruch

United States Geological Survey: Staff Publications

Over the past few decades a generally accepted conceptual model for the thermomechanics of the San Andreas fault was based on three factors believed to have been supported by observation: (1) maximum horizontal shear stress increases with depth in the crust at the rate of 7-8 MPa/km (as indicated by measurements in relatively shallow boreholes), roughly the same rate of shear stress increase as in other regions [e.g., McGarr et al., 1982], (2) the maximum horizontal stress direction in the vicinity of the fault was oriented at about 300-45 ° to its strike (as indicated by the predominance of right-lateral …

Stress Field Constraints On Intraplate Seismicity In Eastern North America, Mary Lou Zoback

United States Geological Survey: Staff Publications

Focal mechanisms of 32 North American midplate earthquakes (m_b = 3.8-6.5) were evaluated to determine if slip is compatible with a broad-scale regional stress field derived from plate-driving forces and, if so, under what conditions (stress regime, pore pressure, and frictional coefficient). Using independent information on in situ stress orientations from well bore breakout and hydraulic fracturing data and assuming that the regional principal stresses are in approximately horizontal and vertical planes ( ± 10 °), the constraint that the slip vector represents the direction of maximum resolved shear stress on the fault plane was used to calculate relative …

A Brief Literature Review Of Open-Channel Current Meter Testing, Kirk G. Thibodeaux

United States Geological Survey: Staff Publications

The U.S. Geological Survey (USGS) has undertaken the task of conducting an evaluation of the USGS's standard water-flow current meter, the Price type-AA current meter. The first part of the USGS's task was to conduct a comprehensive literature review to determine the extent and types of testing that has been conducted to evaluate the performance of various types of current meters used for open-channel flow measurements. The meter types included in the review were the vertical-axis mechanical type, the horizontal-axis mechanical type, the electromagnetic type, and the point-velocity acoustic (ultrasonic) type current meters. The review revealed that current meters have …

Topographic Effects On Stormflow Acidity, David Wolock

United States Geological Survey: Staff Publications

This paper describes the theoretical and observed effects of topography on stormflow acidity in upland, forested watersheds. The theoretical effects were determined by a sensitivity analysis using the hydrologic model TOPMODEL. The observed effects were determined by an analysis of topographic and stormflow acidity data collected from eight watersheds in Wales, Great Britain. Results of the analyses indicated that the observed effects of topography were consistent with the theoretical expectations; that is, topography has an important effect on flow path, and that flow path, in turn, has an effect on stormflow acidity.

Incorporating Hydraulic Structures In An Open-Channel Model, Eric D. Swain

United States Geological Survey: Staff Publications

The open-channel flow model, BRANCH, is a routinely used numerical tool for modeling rivers, canals, and waterway networks. Although a simplified hydraulic structure representation is included in the model, no universal subroutine that can represent hydraulic structures by their rating curve equations has been included in the BRANCH model.

Accordingly, a subroutine has been developed that specifies flow through a structure by a stage-discharge relation. The structure flow equation is used to generate coefficients in the solution matrix that represent the structure in the same computational format as the open-channel flow equations. Field applications have shown that this new subroutine …

Network Applications Of The Usgs Branch Model, Raymond W. Schaffranek

United States Geological Survey: Staff Publications

Applications of a numerical model for simulating unsteady flow in dendritic or interconnected open-channel networks are presented to demonstrate the model's potential for addressing environmental problems and formulating engineering decisions in water-resources investigations. The model is computationally robust and readily adaptable to a broad spectrum of hydraulic conditions and open-channel configurations. The four-point, implicit, finite difference model has been implemented on numerous open-channel reaches and networks in support of various water-resources investigations conducted within the U.S. Geological Survey. In this paper, network applications of the model to a residential canal system in Cape Coral, Florida; to a distributary system of …

Ages Of The Whitewater And Fairhaven Tills In Southwestern Ohio And Southeastern Indiana, Barry B. Miller, William D. Mccoy, William J. Wayne, C. Scott Brockman

Department of Earth and Atmospheric Sciences: Faculty Publications

Alloisoleucine/isoleucine (aIle/Ile) ratios obtained from fossil mollusc shells collected at localities in southwestern Ohio and southeastern Indiana, where they occur in silt beds associated with the Whitewater and Fairhaven tills, indicate a pre-Wisconsinan age for these tills, which had previously been thought to be early or middle Wisconsinan.

The aIle/Ile ratios in shells from beneath the buried soil (Sidney soil) and till exposed near Sidney, Ohio, are most similar to values in shells obtained from Illinoian sediments at Clough Creek in Hamilton County, Ohio; Mechanicsburg southwest, Illinois; and Trousdale Mine in Vermillion Co., Indiana. The first well-developed weathering profile in …

Groundwater-Level Changes In Nebraska, Predevelopment To Fall 1992, Conservation Survey Division, U.S. Geological Survey

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Resource News-July/August 1992

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Geologic Bedrock Map Of Nebraska, R. R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Description Of Rocks From A Core Drilled At A Potential Low-Low Level Radioactive Waste Site In Nemaha County, R. R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Dixon County Test Hole Logs, Raymond R. Burchett, Frank A. Smith

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Boone County Test Hole Logs, Raymond R. Burchett, Frank A. Smith

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Wheeler County Test Hole Logs, Raymond R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Paleontology Of The Cretaceous Of The Central Kerguelen Plateau, David K. Watkins, Patrick G. Quilty, Barbara A.R. Mohr, Shaozhi Mao, J. E. Francis, Carole T. Gee, Millard F. Coffin

Department of Earth and Atmospheric Sciences: Faculty Publications

A synthesis of the Cretaceous calcareous nannofossil, foraminifer, terrestrial and marine palynomorph, macrofauna, and macroflora data from drill sites on the Central Kerguelen Plateau indicates a complex sedimentary history spanning the Albian through the Maestrichtian. Nonmarine Albian sediments from the eastern part of the central plateau record the initial colonization and subsequent succession of plant communities on the basaltic islands left by edifice-building events during the Early Cretaceous. The eastern and northern parts of the central plateau foundered during the early Late Cretaceous. Disconformity-bounded sequences of pelagic calcareous sediment accumulated there throughout the Cenomanian to early Campanian. Following a widespread …

Upper Cretaceous Nannofossils From Leg 120, Kerguelen Plateau, Southern Ocean, David K. Watkins

Department of Earth and Atmospheric Sciences: Faculty Publications

Drilling on the Kerguelen Plateau during Leg 120 cored the most complete, best preserved record of the Late Cretaceous of the Southern Ocean to date. Two calcareous pelagic sedimentary sections (Sites 747 and 750) provide a record from the upper Turonian(?)-lower Coniacian through the Maestrichtian. Two major disconformities interrupt the record: upper Coniacian-lower Santonian and mid-Campanian. Site 748 contains a Campanian-Maestrichtian record of neritic sedimentation dominated by nannofossil-bearing, intermittently silicified, glauconitic bioclastic grainstones to wackestones. Parts of the upper Maestrichtian and the mid-Campanian are absent at this site.

A set of 21 biostratigraphic events were used to correlate these sections. …

8. Cretaceous Subtropical Weathering Followed By Cooling At 60°S Latitude: The Mineral Composition Of Southern Kerguelen Plateau Sediment, Leg 120, Mary Anne Holmes

Department of Earth and Atmospheric Sciences: Faculty Publications

Kaolinite, goethite, minor hematite, and gibbsite were found in fluvial upper Lower Cretaceous basal sediment from the Southern Kerguelen Plateau, Sites 748 and 750, 55°S latitude. This mineral assemblage, derived from the weathering of basalt, indicates near-tropical weathering conditions with high orographic rainfall, at least 100 cm per year. The climate deteriorated by the Turonian or Coniacian, as indicated by the decline in kaolinite content of this sediment.
The Upper Cretaceous sediment at Site 748 consists of 200 m of millimeter-laminated, sparsely fossiliferous, wood-bearing glauconitic siltstone and clay stone with siderite concretions deposited on a shelf below wave base. Some …

9. Composition And Origin Of Cr-Rich Glauconitic Sediments From The Southern Kerguelen Plateus (Site 748), Peter Rene Bitschene, Mary Anne Holmes, James Brezza

Department of Earth and Atmospheric Sciences: Faculty Publications

Five hundred meters of a unique Upper Cretaceous Cr-rich glauconitic sequence (Unit III) that overlies a 3-m-thick alkali-basalt flow with underlying epiclastic volcanogenic sediments was drilled at ODP Leg 120 Site 748. The Cr-rich glauconitic sequence is lithostratigraphically and biostratigraphically divided into three subunits (IIIA, IIIB, IIIC) that can also be recognized by the Cr concentration of the bulk sediment, which is low (<200 ppm) in Subunits IIIC and IIIA and high (400-800 ppm) in Subunit IIIB. The Cr enrichment is caused by Cr-spinel, which is the only significant heavy mineral component beside Fe-Ti ores. Other Cr-bearing components are glauconite pellets and possibly some other clay minerals.
The glauconitic sequence of Subunit IIIB was formed by reworking of glauconite and volcanogenic components that were transported restricted distances and redeposited downslope by mass-transportation processes. The site of formation was a nearshore, shallow inner shelf …

Ecological Aspects Of Burrowing Owl Nesting Strategies In The Nebraska Panhandle, Martha J. Desmond

School of Natural Resources: Dissertations, Theses, and Student Research

No abstract provided.

Bird Response To Monofilament Lines At Backyard Feeders, Kimberly K. Kessler

School of Natural Resources: Dissertations, Theses, and Student Research

No abstract provided.

Groundwater Levels In Nebraska, 1990, Gregory V. Steele, Perry B. Wigley

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Biology And Ecology Of Dioryctria Ponderosae Dyar And Dioryctria Tumicolella Mutuura, Munroe And Ross, Mark A. Brohman

School of Natural Resources: Dissertations, Theses, and Student Research

No abstract provided.

Biology And Ecology Of Dioryctria Ponderosae Dyar And Dioryctria Tumicolella Mutuura, Munroe And Ross, Mark A. Brohman

School of Natural Resources: Dissertations, Theses, and Student Research

No abstract provided.

Threatened And Endanger Species Of Wetiands And Waterways In Iowa, Kansas, Missouri, And Nebraska, Ann Burruss

United States Environmental Protection Agency: Publications

Wetlands and waterways, including perennial and intermittent streams, creeks, and rivers, are habitats for many rare animal and plant species. Wetlands in many areas continue to decline in acreage and suffer adverse impacts from conversion and development. Waterways are also under pressure from channelization and leveeing.

This study has two major components. First, a series of databases was developed that includes animals and plant species that are wetland or waterway dependent and found in Iowa, Kansas, Missouri, or Nebraska. The databases allow ready access to detailed information on each species and probable locations within each state. The plant and animal …

Effects Of The Conservation Reserve Program On Selected Wildlife Populations In Southeast Nebraska, Justin W. King

School of Natural Resources: Dissertations, Theses, and Student Research

No abstract provided.

Scanning Electron Microscopic Study Of Quartz Sand Surface Features, Ash Hollow Formation, Ogallala Group, Western Nebraska, Patricia E. Helland, Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

In field studies of the late Tertiary Ash Hollow Formation of the Ogallala Group in western Nebraska the alluvial deposits are composed of large volumes of sand and gravel up to large cobbles. Because the current understanding of the climate of the region at the time of deposition does not provide for a source for deposits of this character, a scanning electron microscopic study of the surface features on the quartz sand grains from these sediments was undertaken. Nine samples, collected from locations in Banner, Morrill and Keith Counties, were examined to see if they had one or more of …

Plate Tectonics, Space, Geologic Time, And The Great Plains: A Primer For Non-Geologists, Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

For most Americans, "The Great Plains" evokes images of grasslands, dust storms, prairie fires, Native Americans on horseback, cowboys and wheat lands, and perhaps flat valleys crossed by braided rivers carrying a heavy load of sand and gravel, extremes of weather, and a climate typified by an alternation of droughts and wetter periods. Geologists picture such general images, too, but they also see radical changes in the landscape over periods expressed in millions rather than hundreds of years. Geologically speaking, human activities on the Great Plains are too recent to have much of a place in the broad geologic history …